Function transaction_operations

samples/sample_app.py:403–460

Demonstrate TransactWriteItems and TransactGetItems.

(client)

# ---------------------------------------------------------------------------

def transaction_operations(client) -> None:
    """Demonstrate TransactWriteItems and TransactGetItems."""
    section("Step 7: Transactions (TransactWriteItems + TransactGetItems)")

    # TransactWriteItems — atomically create a new user and their first order
    client.transact_write_items(
        TransactItems=[
            {
                "Put": {
                    "TableName": USERS_TABLE,
                    "Item": {
                        "userId": {"S": "user-004"},
                        "name": {"S": "Diana"},
                        "email": {"S": "diana@example.com"},
                        "age": {"N": "28"},
                    },
                    "ConditionExpression": "attribute_not_exists(userId)",
                },
            },
            {
                "Put": {
                    "TableName": ORDERS_TABLE,
                    "Item": {
                        "customerId": {"S": "user-004"},
                        "orderId": {"S": "ord-401"},
                        "orderDate": {"S": "2026-04-18"},
                        "total": {"N": "99.99"},
                        "status": {"S": "pending"},
                    },
                },
            },
        ],
    )
    print("  ✓ TransactWriteItems: created user-004 + order ord-401 atomically")

    # TransactGetItems — read both back in a single transaction
    resp = client.transact_get_items(
        TransactItems=[
            {
                "Get": {
                    "TableName": USERS_TABLE,
                    "Key": {"userId": {"S": "user-004"}},
                },
            },
            {
                "Get": {
                    "TableName": ORDERS_TABLE,
                    "Key": {
                        "customerId": {"S": "user-004"},
                        "orderId": {"S": "ord-401"},
                    },
                },
            },
        ],
    )
    user = resp["Responses"][0]["Item"]
    order = resp["Responses"][1]["Item"]
    print(f"  ✓ TransactGetItems: {user['name']['S']} has order {order['orderId']['S']} (${order['total']['N']})")